Elastic stability and electronic structure of tantalum boride investigated via first-principles density functional calculations

The elastic properties, electronic structure and thermodynamic behavior of the TaB have been investigated for the first time in this work. Using first-principles plane-wave ultrasoft-pseudopotential density functional theory (DFT), the ground state properties and equation of state of TaB have been obtained. The average zero-pressure bulk modulus of TaB is 302 GPa. By analyzing the elastically anisotropic behavior and the relative structure parameters of TaB, we found that the crystal cell along the b-axis was more compressible than along the a and c axes. The calculated ratio of bulk modulus and shear modulus (B/G) for TaB is 1.58, demonstrating that TaB is rather brittle. From the elastic stiffness constants, we found that TaB in the Cmcm phase is mechanically stable. The calculated hardness of TaB is 28.6 GPa which is close to the previous data. Moreover, using the Gibbs 2 model, the thermodynamic properties such as the thermal expansion and Debye temperature of TaB have been obtained firstly. At the ambient temperature, the Debye temperatures of TaB are 792 K and 845 K from GGA calculation and LDA calculation, respectively.

► We investigated the electronic structure and thermodynamic behavior of the TaB.
► The crystal cell along the b-axis was more compressible than along the a and c axes.
► The calculated ratio of bulk modulus and shear modulus (B/G) for TaB is 1.58.
► The calculated hardness of TaB is 28.6 GPa.
► The Debye temperatures of TaB are 792 K (GGA) and 845 K (LDA).